What should I consider before cosigning on an apartment lease?

If you co-sign, you have no protection. You will have to pay any rent or fees he does not pay. If you want to help, give him cash as a gift toward a deposit or first month's rent. If you cosign and he does not pay, not only do you have to pay, your credit gets dinged.

Consider why your brother has asked you to sign, especially if you do not plan to live in the apartment. By co-signing, you are responsible for the monthly rent, damages, and penalties for lease termination, even in the event of eviction, which would involve paying out the term of the lease. In short, you are have no "protection. "